(Newser)
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Scientists poring over satellite images and topographical charts have discovered a flood of new islands. A study has identified 657 new barrier islands around the world, bringing the total number of islands in the world to 2,149, LiveScience reports. Such islands tend to occur in chains, forming a series of small land masses parallel to coastlines as deposits of sand and sediment build up over time.

Among the islands previously overlooked is a 54-island chain in Brazil stretching for hundreds of miles off the coast of a mangrove forest south of the Amazon river. Older satellite images didn't show a clear separation between the islands and mangrove. The researchers say their work will help identify barrier islands in danger of disappearing due to development and rising sea levels. A barrier island held in place by sea walls and jetties "essentially becomes a sitting duck unable to respond to the changes occurring around it," they warn.